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Re: 340 6 pack intake porting???
[Re: superwrench]
#1486869
08/20/13 09:55 PM
08/20/13 09:55 PM
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Joined: Jan 2003
Posts: 15,457
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,457
Omaha Ne
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Im sure even with the stock 6 pack and carbs on top of a good 416" i will have no trouble seeing 11.50's and maybe quicker before they toss me out of the strip for no bar. 
The 6 Pack will be an easy way to slow you down. 
 Never say that.....I just ran 10.80's last weekend.
Everyone says that I'd run 10.60's with a good single plane and 4 bbl....not that I don't believe them, but why change when I'm having a blast making mine run quicker and quicker. 
 
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Re: 340 6 pack intake porting???
[Re: RobX4406]
#1486871
08/21/13 12:25 AM
08/21/13 12:25 AM
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Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
RobX4406
I Live Here
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I Live Here
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
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The big block intake is a different deal than the SB one...
Which part of this did you big block guys that suffer from reading comprehension issues miss?
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Re: 340 6 pack intake porting???
[Re: ademon]
#1486872
08/21/13 12:13 PM
08/21/13 12:13 PM
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Joined: Jan 2003
Posts: 4,737
Moved to N.E. Tennessee
GomangoCuda
master
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master
Joined: Jan 2003
Posts: 4,737
Moved to N.E. Tennessee
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Quote:
I think the stock carbs out-flow the mechanicals. FWIW I'm pretty much under 11.50 (unless I blow the tires up) and haven't been asked to leave yet. They key is to put 12.0 @ 115 on your tech card. Usually the guy handing out slips isn't looking inside the car for a cage.
The 4782/4783 mechanicals have exactly the same venturi diameter, booster and throttle bore diameter as the original carbs so obviously they would flow the same. Just because they look similar to the old Ford 3x2 don't assume they are the same. They are in fact much larger and are a nice upgrade on the Ford as well.
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there rated at 1355cfm, i know when compared to 4bbl rating i think they are in the 975 cfm range same as the stock vacuum carbs. The manifold ports are quite a bit smaller than the gasket so at the very least i will gasket match them to the heads.
As far as cfm goes there is much speculation about actual flow capability vs a large 4bbl. The old Mopar race manuals said that the outers flow 425 cfm and the center flows 295cfm. Not coincidently the outers have the same venturis and throttle bores as an 850 cfm double pumper and the center has the same as the primaries of a 590 cfm holley 4 barrel. So basically the six pack is an 850 cut in half with the front of a 590 put in the middle. 850+295=1145cfm.
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The big block intake is a different deal than the SB one...
I would have to agree with that. Probably neither one can take full advantage of the carbs cfm but the small block intake is certainly smaller than the bigblock.
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Re: 340 6 pack intake porting???
[Re: GomangoCuda]
#1486873
08/21/13 01:16 PM
08/21/13 01:16 PM
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Joined: Jan 2004
Posts: 4,576
Motor City
6PKRTSE
master
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master
Joined: Jan 2004
Posts: 4,576
Motor City
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We just did a 416 (340 sixpack) engine. We sent the sixpack intake out to extrude hone. Engine made 580HP/550TQ on the dyno w a mild hyd/rlr cam.
1963 Belvedere 440 Max Wedge Tribute
1970 Charger R/T S.E. 440 Six Pack
1970 Challenger R/T, 528 Hemi
1970 Charger 500 S.E. 440 4 BBL
1970 Plymouth Road Runner 383
1974 Chrysler New Yorker 440
1996 2500 RAM 488 V-10 4X4
2004 3500 Dually Cummins 4x4
2012 Challenger R/T Classic.
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Re: 340 6 pack intake porting???
[Re: GomangoCuda]
#1486874
08/21/13 08:55 PM
08/21/13 08:55 PM
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Joined: Feb 2005
Posts: 4,318
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,318
Prospect, PA
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Quote:
As far as cfm goes there is much speculation about actual flow capability vs a large 4bbl. The old Mopar race manuals said that the outers flow 425 cfm and the center flows 295cfm. Not coincidently the outers have the same venturis and throttle bores as an 850 cfm double pumper and the center has the same as the primaries of a 590 cfm holley 4 barrel. So basically the six pack is an 850 cut in half with the front of a 590 put in the middle. 850+295=1145cfm
You've missed some key aspects: 1) The boosters in the outboard carbs are different than an 850 (i.e. take up more space), 2) the throttle shafts are not slabbed like an 850 (again, taking up more cross sectional area in the throttle bore, and 3) the throttle plates are aluminum and considerably thicker than in an 850. There are notable differences between an 850 and the outboard carbs.
If the six pack carbs flow 1350 cfm @ 3.0" Hg, and the 850 @ 1.5" Hg, as stated by Holley, then the science and associated math is simple. The six pack will flow 955 cfm @ 1.5" Hg. The question in my mind is if Holley"s numbers are real.
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Re: 340 6 pack intake porting???
[Re: ademon]
#1486875
08/22/13 08:47 AM
08/22/13 08:47 AM
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Joined: Oct 2003
Posts: 2,403
WASHINGTON, PA
11secaarcuda
top fuel
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top fuel
Joined: Oct 2003
Posts: 2,403
WASHINGTON, PA
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I shift my AAR at 7000 and it has hit the rev limiter quite a few times set at 7500. My 340 six pack loves to rev. Best time 12.3 @ 109. It slows down if I shift it anywhere lower than 6600 rpms. It has also gone 11.90 with a small shot of nitrous through the 6 pack intake.
Nice! Is that the old Eddy intake or the Mopar? I thought I read somewhere that the intake hit a flat spot around 6,200 rpm but then made power again past that if pushed higher.
Stock intake and stock carbs. Carbs tuned by me (modified the plates in the secondaries, lighter springs, and appropriate power valve). And yes, I did port match the intake manifold runners to the head ports, but just to match up (smoothly transition) the size of the ports from the intake manifold to the heads. By the way, my AAR ran slower when I put on an M1 and a single 4 barrel.
67 Dart GT 340 4 speed
70 AAR Cuda 408 6 barrel
96 Indy Ram original owner
2011 Hemi Durango
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Re: 340 6 pack intake porting???
[Re: BSB67]
#1486878
08/22/13 06:01 PM
08/22/13 06:01 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
OP
master
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OP
master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Quote:
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As far as cfm goes there is much speculation about actual flow capability vs a large 4bbl. The old Mopar race manuals said that the outers flow 425 cfm and the center flows 295cfm. Not coincidently the outers have the same venturis and throttle bores as an 850 cfm double pumper and the center has the same as the primaries of a 590 cfm holley 4 barrel. So basically the six pack is an 850 cut in half with the front of a 590 put in the middle. 850+295=1145cfm
You've missed some key aspects: 1) The boosters in the outboard carbs are different than an 850 (i.e. take up more space), 2) the throttle shafts are not slabbed like an 850 (again, taking up more cross sectional area in the throttle bore, and 3) the throttle plates are aluminum and considerably thicker than in an 850. There are notable differences between an 850 and the outboard carbs.
If the six pack carbs flow 1350 cfm @ 3.0" Hg, and the 850 @ 1.5" Hg, as stated by Holley, then the science and associated math is simple. The six pack will flow 955 cfm @ 1.5" Hg. The question in my mind is if Holley"s numbers are real.
I looked at my outboard and it has down leg boosters the center carb has down leg but with the tube protruding into the center, the shafts are half, not sure if "slabbed" but there not the round type that the throttle plate sits between, the throttle is metal and only .038 thick. Looks like an old 800 and 850 dp I had . 
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Re: 340 6 pack intake porting???
[Re: ademon]
#1486879
08/22/13 08:55 PM
08/22/13 08:55 PM
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Joined: Feb 2005
Posts: 4,318
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,318
Prospect, PA
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Quote:
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Quote:
As far as cfm goes there is much speculation about actual flow capability vs a large 4bbl. The old Mopar race manuals said that the outers flow 425 cfm and the center flows 295cfm. Not coincidently the outers have the same venturis and throttle bores as an 850 cfm double pumper and the center has the same as the primaries of a 590 cfm holley 4 barrel. So basically the six pack is an 850 cut in half with the front of a 590 put in the middle. 850+295=1145cfm
You've missed some key aspects: 1) The boosters in the outboard carbs are different than an 850 (i.e. take up more space), 2) the throttle shafts are not slabbed like an 850 (again, taking up more cross sectional area in the throttle bore, and 3) the throttle plates are aluminum and considerably thicker than in an 850. There are notable differences between an 850 and the outboard carbs.
If the six pack carbs flow 1350 cfm @ 3.0" Hg, and the 850 @ 1.5" Hg, as stated by Holley, then the science and associated math is simple. The six pack will flow 955 cfm @ 1.5" Hg. The question in my mind is if Holley"s numbers are real.
I looked at my outboard and it has down leg boosters the center carb has down leg but with the tube protruding into the center, the shafts are half, not sure if "slabbed" but there not the round type that the throttle plate sits between, the throttle is metal and only .038 thick. Looks like an old 800 and 850 dp I had .
Interesting. Mine are original 1969 carbs. The boosters are downleg, just larger than on my 4781-2, 850. I also have recently acquired from Holley assembled base plates and they also have the full diameter throttle shaft and thicker plates.
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Re: 340 6 pack intake porting???
[Re: ademon]
#1486880
08/22/13 09:12 PM
08/22/13 09:12 PM
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Joined: Jan 2003
Posts: 4,737
Moved to N.E. Tennessee
GomangoCuda
master
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master
Joined: Jan 2003
Posts: 4,737
Moved to N.E. Tennessee
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Original carbs are not the same as the mechanicals in many ways. The 4783 mechanical outer carb does not have the thick throttle plates.
I'll have to remove the front carb from my car to compare the boosters and throttle shaft with a 4781 850dp. I'll be back shortly.
In theory, there is no difference between theory and practice. In practice, there is.
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Re: 340 6 pack intake porting???
[Re: GomangoCuda]
#1486881
08/22/13 09:45 PM
08/22/13 09:45 PM
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Joined: Jan 2003
Posts: 4,737
Moved to N.E. Tennessee
GomangoCuda
master
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master
Joined: Jan 2003
Posts: 4,737
Moved to N.E. Tennessee
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I measured the boosters and they are exactly the same.
Last edited by GomangoCuda; 08/22/13 09:52 PM.
In theory, there is no difference between theory and practice. In practice, there is.
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Re: 340 6 pack intake porting???
[Re: GomangoCuda]
#1486882
08/22/13 09:49 PM
08/22/13 09:49 PM
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Joined: Jan 2003
Posts: 4,737
Moved to N.E. Tennessee
GomangoCuda
master
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master
Joined: Jan 2003
Posts: 4,737
Moved to N.E. Tennessee
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Exact same slabbed throttle shaft as 4781. The stamped numbers on the throttle plates are even the same.
I still believe that two 4783s equals one 4781. And then there's the matter of 300 more cfm stuffed in between them.
For those that don't know, the 4782/4783 mechanical carbs were not OEM on anything. They were available over the counter in the 1970's from both Holley and Mopar. They use side hung float bowls to get extra space for full metering blocks. Unlike the OEM carbs, the idle mixture is not adjustable on the outer carbs. Edelbrock supplied the linkage and a fuel log. The linkage and fuel log have not been available for decades and you have to make your own. Fuel lines are an adventure as they are on the wrong side and the front carb fitting interferes with the 70 and up aircleaner base. I had to make 3/8" spacers to raise the base up for clearance. The A12 aircleaner fits fine without spacers.
Last edited by GomangoCuda; 08/22/13 10:24 PM.
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